Mobile communication systems have been developed in order to make people free to move away from fixed telephone terminals without, however, making them more difficult to reach. With an increasing usage of data transfer services in offices, various kinds of data services have been introduced to the mobile communication systems as well. Portable computers enable efficient data processing wherever the user may be. Mobile communication networks, in turn, provide users with an efficient access network for mobile data transfer, the access network providing access to actual data networks. For this purpose, various new forms of data service are being planned in present and future mobile communication networks. Mobile data transfer is particularly well supported by digital mobile communication systems, such as the Pan-European mobile communication system, GSM (Global System for Mobile Communication).
A new service in the GSM system is provided by GPRS (General Packet Radio Service), which is one of the topics for GSM stage 2+ standardization work being done in ETSI (European Telecommunication Standard Institute). The GPRS operational environment is constituted by one or more subnetwork service areas which are inter-connected by a GPRS Backbone Network. The subnetwork comprises a group of packet data service nodes SN, herein referred to as serving GPRS support nodes SGSN, each of which is connected to the GSM mobile communication network so that it is able to provide mobile data terminal equipments with a packet data service via a multitude of base stations i.e. cells. The mobile communication network in between offers a packet switched data transfer between the support node and the mobile data terminal equipments. The different subnetworks, in turn, are connected to an external data network, e.g. to a packet switched public data network PSPDN, via specific gateway GPRS support nodes, GGSN. Thus, the GPRS service provides packet data transfer between mobile data terminal equipments and external data networks with the GSM network serving as an access network. One of the features of the GPRS service network is that it operates almost independently of the GSM network with the “conventional” GSM network services.
One of the problems is how to carry out charging in the GPRS network. User-related data transmission statistics, used for charging the user, are normally gathered at the serving GPRS support nodes SGSN and at the gateway GPRS support nodes GGSN. The SGSN collects information about the radio interface usage and the GGSN collects information about the data network usage. The number of SGSNs and GGSNs in an MSC service area can be quite high, tens or even hundreds of nodes. However, no suggestions exist as to how to carry out charging using such scattered charging information. In the GSM mobile communication network, the billing records (Call Detailed Records) are typically generated at the mobile communication network or in an Intelligent Network IN coupled thereto. However, there are no direct interfaces from the GPRS system to the mobile network or the IN suitable also for the GPRS charging. A further problem is that the billing centers and the interfaces they use have not been standardized even in the mobile communication networks and are consequently different for every operator. This would require implementing different interfaces in different GPRS networks. Similar problems may also occur in other packet radio networks of the GPRS network type.